Semiconductor devices have dramatically decreased in size in the last few decades. Modern devices include features that are 350 nanometers, 90 nanometers, and 65 nanometers in size and often even smaller. As device and feature sizes continue to shrink, processing methods need to be improved.
Many semiconductor substrates are subjected to multiple lithographic operations that involve deposition and removal of photoresist materials onto the substrates. Each time a photoresist is deposited onto a substrate, it has to be stripped away (e.g., etched) after lithographic processing. Conventionally, photoresist stripping involves plasma ashing followed by washing with a strong acid and hydrogen peroxide. However, many materials commonly used in integrated circuits can be easily damaged by these photoresist stripping techniques.